Supernatural bargain
In short: A motif in which a character receives extraordinary help in exchange for a price or on a condition.
Motif
How does it work in the tale?
In the Cantuña legend, the condition turns on finishing a building. In Rumpelstiltskin, the helper who spins straw into gold names a price, then offers guessing his name as a way out. Look for the promise each character makes and who gets to set the terms.
When does the price of the bargain change?
In Rumpelstiltskin, jewellery pays for the first two nights of spinning. On the third night, the helper asks for a child who has yet to be born. As queen, the woman is offered a new condition. She can keep her child if she learns the helper’s name. Reading the bargains in sequence shows how the earlier payments give way to a much larger promise.